In the normal course of use, deposits form on many parts of an internal combustion engine and components. Deposits which form on various parts of a carburetor are particularly vexing, leading to a decrease in overall efficiency of combustion attended by increasing gas consumption and undesirable exhaust gas emissions. Deposits also tend to accumulate on other parts of the fuel induction system, such as valves and ports, with similar adverse effects.
An object of this invention is to provide additives which when added to fuel oils, especially gasoline, in minor amounts act as an effective carburetor detergent. Another object of this invention is to provide additives which when added to fuel oils, especially gasolines, in minor amounts materially reduce deposits accumulating on valves and ports of internal combustion engines. Such materials may have additional desirable properties when added to gasoline and used in internal combustion engines. For example, materials of this invention may inhibit gum formation, may act as anti-stalling or carburetor de-icing agents, as corrosion inhibitors, and so forth. Still another object is to provide additives effective as carburetor detergents at concentrations less than about 100 parts per million. Materials in the prior art generally are required to be used at a concentration over about 100 parts per million, as exemplified in U.S. Pat. No. 4,134,846.
Materials bearing a superficial resemblance to those of the present invention have found varying uses in the prior art. Vicinal alkanol amines containing 20 or fewer carbon atoms have been used as sedimentation inhibitors in blended burner oils, U.S. Pat. No. 2,695,222. The materials described there are monoamines, preferably primary amines, whereas the additives described herein invariably are non-primary polyamine alkanols. The reaction product of N-alkyl ethylenediamine or propylenediamine with varying weight ratios of alkylene oxides containing 4 or fewer carbon atoms has been claimed to be effective in stabilizing fuel oils against oxidative deterioration, U.S. Pat. No. 3,092,475. However, the materials described herein result from higher alkylene oxides, including internal epoxides, and especially epoxides containing branched chains.
The condensation product of diamines with ethylene or propylene oxide described in U.S. Pat. No. 2,902,354 results from one mole proportion oxide per amino hydrogen. In contrast, the condensation products described herein result from one mole proportion oxide per primary amino group. This difference results in several important distinguishing characteristics for the products of this invention. One distinction is that in forming the products herein applicant never uses more than about half the mole proportion of oxide required by the patentee. Another distinction is that where the polyamine bears a secondary amino group, the condensation products of this invention have the same, unchanged secondary amino groups. A third important distinction is that in the products of this invention a primary amino group is transformed into a secondary amino group--i.e., the amino nitrogen bears one hydrogen atom--whereas the patentee's products are characterized by transformation of all amino groups into tertiary amino groups--i.e., the amino nitrogen bears no hydrogen atoms. A corollary of this distinction is that in the case of polyamines bearing two primary amino groups the materials herein are dihydric alcohols, whereas the patentee's materials are tetrahydric alcohols; in all other cases the materials herein are monohydric alcohols, whereas the patentee's materials are at least trihydric alcohols.